It's just an external bolt hold open, I don't believe it's designed to drop the bolt at all.
If you look at the bolt itself there is a little triangular area on the left side, and the top part of the bolt hold open is almost like a fishing hook.
When you try to release the bolt it's acting similar to a trigger sear, and you have a few angles and other forces to overcome before the bolt drops. This is different in an AR which works because the bolt hold open is just a flat plate that rests against the bolt, and levers out of the way vertically.
With the WK/MCR you should just pull the charging handle back and release. The hold open spring will pop it down and out of the way and your bolt will be cleared to go all the way forward.
I could be wrong, but I believe that if you use the hold open, as a bolt release often enough, you'll probably mar it up and run into other issues/breakage.